SIZE-EXCLUSION CHROMATOGRAPHY OF CROSS-LINKED SUPERABSORBENT POLYMERS

Superabsorbent polymers are cross-linked poly(acrylic acid) with some degree of neutralization. These polymers have found extensive use as constituents in personal care products such as sanitary napkins, incontinent devices, and disposable baby diapers that absorb body fluids. Polymer networks are formed, which makes the chromatography of these materials impossible. In this study, hydrolysis under heat and high pH was used to break the cross-links, which allows for traditional size-exclusion chromatography to determine molecular weight and molecular weight distribution of the primary chains. For the chromatography, TSK-GEL(R)dagger PWXL columns and TSK-GEL PW columns were used. The mobile phase was buffered with sodium chloride and sodium phosphate salts to eliminate ionic interactions. Detection was by refractive index. (C) 1995 John Wiley and Sons, Inc.